The fins of automobile radiators are joined to radiator tubes and function to dissipate the heat from the heated coolant flowing through the tubes to the atmosphere.
The properties required of the fins, therefore, include thermal resistance and thermal conductivity. As a material that meets these property requirements, tin-containing copper has in recent years come into use.
Nethertheless, there is growing concern about serious corrosion of automobile radiator fins with its fatal effects upon the heat-dissipating function and life of the radiators. These and other problems arise from the aggravation of the environmental conditions with the recent increase in the concentrations of SO.sub.2 gas and exhaust emissions in the air, exposure to salty air in coastal regions, deleterious action of melting agents sprinkled over roads after snowfall, and other adverse factors. In addition, the recent tendency in the automobile industry to manufacture vehicles lighter in weight than before has been accompanied with the adoption of thinner radiator fins, so that even slight corrosion of the fins can lead to deteriorated radiator performance.
Under these circumstances the tin-containing copper sheets currently in use for the fabrication of fins are rather susceptible to the corrosive attacks, and therefore the development of a more excellently corrosion-resistant copper alloy has been desired.